how to call a function onclick in react code example

Example 1: react onclick parameter

import React from 'react';

const ExampleComponent = () => {
  
  function sayHello(name) {
    alert(`hello, ${name}`);
  }
  
  return (
    <button onClick={() => sayHello('James')}>Greet</button>
  );
}

export default ExampleComponent;

Example 2: react button onclick

import React, { Component } from 'react';

class App extends Component {
  
  constructor(props) {
    super(props);
    this.sayHello = this.sayHello.bind(this);
  }

  sayHello() {
    alert('Hello!');
  }
  
  return (
    <button onClick={this.sayHello}>
      Click me!
    </button>
  );
}

export default App;

Example 3: react button onclick

import React from 'react';

function App() {

  function sayHello() {
    alert('Hello!');
  }
  
  return (
    <button onClick={sayHello}>
      Click me!
    </button>
  );
}

export default App;

Example 4: react button onclick

<button onClick={sayHello}>Click</button>